A load sensor includes a base substrate having two holes as two fixing portions to a frame member as a detection object, a pair of strain detecting elements provided on a surface of the base substrate, and input-output terminals provided on the surface of the base substrate. The strain detecting elements are arranged in a region that is between the holes and is opposite the input-output terminals with respect to at least one of the holes.
1. A load sensor comprising:
a base substrate having at least first and second fixing portions to receive first and second fixing members, respectively, which fix the base substrate to a detection object, the first and second fixing portions transmitting a load applied to the detection object to the base substrate via the first and second fixing members, respectively;
a strain detecting element provided on a surface of the base substrate in a region between the first and second fixing portions;
an input-output terminal provided on the surface of the base substrate outside the region between the first and second fixing portions; and
a reference resistance element provided on the surface of the base substrate outside the region between the first and second fixing portions, the reference resistance forming a bridge circuit together with the strain detecting element,
wherein the strain detecting element detects a load corresponding to a load applied to a strain detection portion of the detection object between the first and second fixing members.
2. The load sensor according to claim 1 , wherein the reference resistance element is arranged on an opposite side of the input-output terminal with respect to the region between the first and second fixing portions.
3. The load sensor according to claim 1 , wherein the strain detecting element, the input-output terminal, and the reference resistance element are formed on a same plane by screen printing.
4. The load sensor according to claim 1 , wherein the base substrate includes:
a bent portion; and
first and second flat plates extending from the bent portion in a respective direction, each of the first and second flat plates having a surface facing the detection object with a gap provided therebetween by the fixing members,
wherein the first and second fixing portions are provided on the first and second flat plates, respectively, and
wherein the strain detecting element, the input-output terminal, and the reference resistance element are provided on the surface of the first flat plate facing the detection object.
5. The load sensor according to claim 4 ,
wherein the strain detecting element is arranged in a region between the first fixing portion and the bent portion near the bent portion, and
wherein the reference resistance element is arranged in a region opposite the bent portion with respect to the first fixing portion.
6. The load sensor according to claim 5 , wherein the base substrate has a substantially L-like shape formed by a cross section of the first flat plate, the bent portion, and the second flat plate.
7. The load sensor according to claim 4 , further comprising a thermistor on the same surface of the first flat plate having the strain detecting element, the input-output terminal, and the reference resistance element.
8. A load sensor comprising:
a base substrate having at least first and second fixing portions to receive first and second fixing members, respectively, which fix the base substrate to a detection object, the first and second fixing portions transmitting a load applied to the detection object to the base substrate via the first and second fixing members, respectively;
a strain detecting element provided on a surface of the base substrate in a region between the first and second fixing portions; and
an input-output terminal provided on the surface of the base substrate outside the region between the first and second fixing portions,
wherein the strain detecting element detects a load corresponding to a load applied to a strain detection portion of the detection object between the first and second fixing members,
and wherein the strain detecting element includes a pair of first and second detecting elements.
9. The load sensor according to claim 8 , further comprising:
a third fixing portion arranged between the first and second detecting elements between the first and second fixing portions, the third fixing portion receiving a third fixing member,
wherein the first detecting element detects a load corresponding to a first load applied to a first strain detection portion between the first and third fixing members, and the second detecting element detects a second load applied to a second strain detection portion between the third and second fixing members.